Multiscale enhancement mechanism of low-temperature performance for degraded recycled waste rubber asphalt binders: MD simulation and microscopic investigation

Desulfurization and degradation are important processes to facilitate the storage of waste rubber asphalt and improve its utilization. However, this process is extremely complex and the mechanisms underlying the resulting performance enhancement remain unclear. This study aims to investigate the multiscale mechanism of rubber degradation and its impact on the low-temperature performance of degraded rubber modified asphalt (DRMA) binder through differential scanning calorimetry (DSC), bending beam rheometer (BBR), fluorescence microscopy (FM) and Fourier transform infrared spectroscopy (FTIR) tests and molecular dynamics (MD) simulations. The results showed that as the degradation of rubber powder deepens, lightweight components decomposed from the rubber are more easily dissolved into the virgin asphalt, thus improving its dispersion. In addition, the small molecular structure after rubber degradation penetrates and fills the aggregation space between asphalt molecules, effectively increasing the molecular activity of asphalt, thus enhancing the low-temperature performance of asphalt.